Release film composed of a laminate

Abstract

A release film composed of a laminate comprising (A) a layer of a flexible polyolefin as an interlayer, and (B) two layers of crystalline polymethylpentene formed on both sides of the interlayer.

We claim: 
     
       1. A release film composed of a laminate comprising (A) a layer of flexible polyolefin as an interlayer, and   (B) two layers formed on both sides of the interlayer said two layers consisting essentially of crystalline polymethylpentene.   
     
     
       2. The release film of claim 1 in which the flexible polyolefin is a copolymer or multi-component copolymer of alpha-olefins selected from the groups consisting of ethylene, propylene, 1-butene, 1-pentene, 1-hexene and 4-methyl-1-pentene. 
     
     
       3. The release film of claim 1 in which the flexible polyolefin a copolymer selected from the group consisting of copolymers of ethylene and acrylates or methacrylates, a copolymer of ethylene with acrylic or methacrylic acid, and partially ionically crosslinked products of these copolymers. 
     
     
       4. The release film of claim 1 in which the crystalline polymethylpentene is a homopolymer of 4-methylpentene-1, or a copolymer of 4-methylpentene-1 with another alpha-olefin. 
     
     
       5. The release film of claim 1 in which the interlayer is composed of a plurality of layers of the flexible polyolefin.